Case Study: Watershed-Scale Restoration within 4 Years – RES Robinson Fork Mitigation Bank
Michael Sachs, PE
RES, LLC
Pittsburgh, PA
Ward Oberholtzer, PE
LandStudies, Inc.
Pittsburgh, PA
RES has completed the assessment, design, permitting, construction and 2+ years of monitoring for the state’s largest mitigation bank: The Robinson Fork Mitigation Bank in Washington County, Pennsylvania. As described by the PA Environment Digest, “ecological restoration project activities will occupy a significant portion of the Robinson Fork Watershed, nearly 7¼ square miles,” or over 30% of the 20 square mile watershed in Phase I. The project accomplished a watershed-scale restoration and included:
50,380.06 feet of stream restoration,
21,888.11 feet of stream rehabilitation,
24,060.34 feet of stream enhancement,
32,415.60 feet of stream preservation,
34.82 acres of wetland creation,
1.96 acres of wetland rehabilitation,
3.07 acres of wetland enhancement, and
2.84 acres of wetland preservation.
Restoration occurred on waters with drainage areas from less than 50 acres to over 20 square miles. Historic and recent impairments included agriculture (legacy sediment), logging, long-wall mining subsidence, and floodplain encroachments including roads and utilities. The design process included developing numerous restoration prototypes for restoring (1) headwater systems with slopes that varied from less than 5% to greater than 25%, (2) narrow waters founded on cobble and bedrock with high boundary stress, (3) wider valleys founded on gravel with lower boundary stress, (4) mainstem prototype for waters greater than 10 square miles, and (5) alluvial fans for transitioning the steep drainage waters into the receiving floodplains using 2-Dimensional hydrodynamic models of proposed restored conditions and existing condition impairments. The project included significant timing constraints to meet crediting or deliverable requirements. The presentation will discuss the topics listed above plus innovative permitting procedures, 2-dimensional modeling aspects, functional ecological uplift, construction techniques, and monitoring results including biological and physical. The speakers would also like to introduce Ohio University’s research on functional and biological recovery continuum resulting from floodplain reconnection, with a goal of comparing long term recovery and function with traditional mitigation projects in the ecoregion.
About Michael Sachs, PE
Mike Sachs joined the RES team in 2017 as a Senior Project Manager, bringing with him over 13 years of experience in the field of civil and water resources engineering for project applications in the transportation, energy, and other markets. As the General Manager, Northeast, Mike oversees planning and execution of all phases of compensatory mitigation and water quality solutions including land acquisition, technical design/permitting, construction, operations and maintenance.
Mike has extensive engineering experience in watershed restoration implementation, floodplain and natural channel design, civil site design, stormwater management, hydrologic and hydraulic modeling, and bridge and dam inspection and rehabilitation. Mike served as a design engineer for the Gatehouse Anchorage System for the Prettyboy Dam in Baltimore County, MD, which was awarded National Rehabilitation Project of the Year in 2010 from the Association of State Dam Safety Officials.
About Ward Oberholtzer, PE
Bachelors Degree - University of Maryland (1986) – Agricultural Engineering w/concentration in Soil and Water Engineering. He is currently employed by Landstudies, Inc. and Century Engineering, Inc. and a Professional Engineer (1991) licensed in Pennsylvania, Maryland and other states. He has expertise in surface and subsurface hydrologic/hydraulic engineering including geomorphic assessments, stream and floodplain restoration, watershed assessment and the interaction of floodplain encroachments and waterway crossings with the natural systems, wetland creation & enhancement and river mechanics and water surface profile modeling. He has worked extensively in Maryland assessing and developing techniques to measure potential long term bed degradation.
The last 17 years, Mr. Oberholtzer has been completing designs and the implementation of stream and floodplain restoration projects including those impacted by “legacy sediments”. These projects include waters with drainage areas over 25 square miles to smaller valleys with slopes greater than 20%. Besides RES Robinson Fork Phase 1 Mitigation Bank, other projects include Big Spring Run – Lancaster County; Broad Creek – Anne Arundel County; Shobers Run – Bedford Springs Golf Course, Pa; Santa Dominga – Lititz, Pa; and Georges Run – Baltimore County. He has also provided many stream stability and scour assessments at waterway crossings throughout the state including bridges and culverts for Maryland State Highway Administration (MDSHA). He has been a consultant employed by Maryland State Highway Administration to assist in the development of procedures and techniques to assess the interaction or stability of the stream and crossing and provide recommendations for new and replacement bridge and culvert crossings. He has also completed watershed assessments identifying historic and recent causes of instability and long and short-term structural and/or non-structural solutions.